Shoe cushioning, body mass and running biomechanics as risk factors for running injury: a study protocol for a randomised controlled trial

INTRODUCTION

Repetitive loading of the musculoskeletal system is suggested to be involved in the underlying mechanism of the majority of running-related injuries (RRIs). Accordingly, heavier runners are assumed to be at a higher risk of RRI. The cushioning system of modern running shoes is expected to protect runners again high impact forces, and therefore, RRI. However, the role of shoe cushioning in injury prevention remains unclear. The main aim of this study is to investigate the influence of shoe cushioning and body mass on RRI risk, while exploring simultaneously the association between running technique and RRI risk.

METHODS AND ANALYSIS

This double-blinded randomised controlled trial will involve about 800 healthy leisure-time runners. They will randomly receive one of two running shoe models that will differ in their cushioning properties (ie, stiffness) by ~35%. The participants will perform a running test on an instrumented treadmill at their preferred running speed at baseline. Then they will be followed up prospectively over a 6-month period, during which they will self-report all their sports activities as well as any injury in an internet-based database TIPPS (Training and Injury Prevention Platform for Sports). Cox regression analyses will be used to compare injury risk between the study groups and to investigate the association among training, biomechanical and anatomical risk factors, and injury risk.

ETHICS AND DISSEMINATION

The study was approved by the National Ethics Committee for Research (Ref: 201701/02 v1.1). Outcomes will be disseminated through publications in peer-reviewed journals, presentations at international conferences, as well as articles in popular magazines and on specialised websites.

TRIAL REGISTRATION NUMBER

NCT03115437, Pre-results.

Effect of Promotional Initiatives on Visits to a Dedicated Website for Physical Activity and Non-Communicable Disease in Luxembourg: An Event Study

The Sport-Santé project and its website (www.sport-sante.lu) promote physical activity for individuals with non-communicable diseases (NCDs) in Luxembourg. Our purpose was to perform an event study analysis to evaluate the effects of communication and promotional initiatives on the number of visits to the Sport-Santé website. Between September 2015 and May 2016, the Sport-Santé website was promoted during different initiatives, including participation in health-related events or publication of articles in local journals. The daily number of visits to www.sport-sante.lu website (i.e., our outcome) was recorded using Google Analytics and compared to a counterfactual collected with its benchmarking tool. The counterfactual was defined as the daily number of visits to websites in the same field. A model was created to evaluate the relationship between the number of visits to www.sport-sante.lu website and the number of visits to similar websites during a control period with no promotional initiatives (from July 2015 to September 2015). The effect of promotional initiatives was subsequently tested, by comparing the actual number of visits to our website (up to 2 days after each event) with the theoretical number of visits predicted by the model. Twenty-two initiatives were identified, of which 11 were participations at major health-related events and 11 publications of popular science articles. Of these 22 initiatives, the event study identified 2 popular science articles and 1 interactive workshop that significantly increased the daily number of visits to the www.sport-sante.lu website. One of the two articles was published on the day before the workshop was held, which did not allow us to distinguish its specific impact. The second article was published in the main national newspaper. This is the first time to our knowledge that an event study analysis has been used to evaluate the impact of promotional initiatives on the number of visits to a dedicated website for physical activity and NCDs. Our results indicate that some initiatives can aid in the number of visits, but in general their impact is limited. To observe an increased rate of participation in physical activity, additional promotional and evaluative strategies should be explored.

Influence of the Heel-to-Toe Drop of Standard Cushioned Running Shoes on Injury Risk in Leisure-Time Runners: A Randomized Controlled Trial With 6-Month Follow-up

BACKGROUND

Modern running shoes are available in a wide range of heel-to-toe drops (ie, the height difference between the forward and rear parts of the inside of the shoe). While shoe drop has been shown to influence strike pattern, its effect on injury risk has never been investigated. Therefore, the reasons for such variety in this parameter are unclear.

PURPOSE

The first aim of this study was to determine whether the drop of standard cushioned running shoes influences running injury risk. The secondary aim was to investigate whether recent running regularity modifies the relationship between shoe drop and injury risk.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

Leisure-time runners (N = 553) were observed for 6 months after having received a pair of shoes with a heel-to-toe drop of 10 mm (D10), 6 mm (D6), or 0 mm (D0). All participants reported their running activities and injuries (time-loss definition, at least 1 day) in an electronic system. Cox regression analyses were used to compare injury risk between the 3 groups based on hazard rate ratios (HRs) and their 95% CIs. A stratified analysis was conducted to evaluate the effect of shoe drop in occasional runners (<6 months of weekly practice over the previous 12 months) versus regular runners (≥6 months).

RESULTS

The overall injury risk was not different among the participants who had received the D6 (HR, 1.30; 95% CI, 0.86-1.98) or D0 (HR, 1.17; 95% CI, 0.76-1.80) versions compared with the D10 shoes. After stratification according to running regularity, low-drop shoes (D6 and D0) were found to be associated with a lower injury risk in occasional runners (HR, 0.48; 95% CI, 0.23-0.98), whereas these shoes were associated with a higher injury risk in regular runners (HR, 1.67; 95% CI, 1.07-2.62).

CONCLUSION

Overall, injury risk was not modified by the drop of standard cushioned running shoes. However, low-drop shoes could be more hazardous for regular runners, while these shoes seem to be preferable for occasional runners to limit injury risk.

Human motor control of landing from a drop in simulated microgravity

Landing on the ground on one's feet implies that the energy gained during the fall be dissipated. The aim of this study is to assess human motor control of landing in different conditions of fall initiation, simulated gravity, and sensory neural input. Six participants performed drop landings using a trapdoor system and landings from self-initiated counter-movement jumps in microgravity conditions simulated in a weightlessness environment by different pull-down forces of 1-, 0.6-, 0.4-, and 0.2 g External forces applied to the body, orientation of the lower limb segments, and muscular activity of 6 lower limb muscles were recorded synchronously. Our results show that 1) subjects are able to land and stabilize in all experimental conditions; 2) prelanding muscular activity is always present, emphasizing the capacity of the central nervous system to approximate the instant of touchdown; 3) the kinetics and muscular activity are adjusted to the amount of energy gained during the fall; 4) the control of landing seems less finely controlled in drop landings as suggested by higher impact forces and loading rates, plus lower mechanical work done during landing for a given amount of energy to be dissipated. In conclusion, humans seem able to adapt the control of landing according to the amount of energy to be dissipated in an environment where sensory information is altered, even under conditions of non-self-initiated falls.

Objective measurements of static anterior and rotational knee laxity

Several devices allow to measure anterior and rotational static knee laxity. To date, the use of rotational laxity measurements in the daily clinical practice however remains to be improved. These measurements may be systematically integrated to the follow-up of knee injuries. Physiologic laxity measurements may particularly be of interest for the identification of risk factors in athletes. Furthermore, knee laxity measurements help to improve the diagnosis of knee soft tissue injuries and to follow up reconstructions. Further prospective follow-ups of knee laxity in the injured/reconstructed knees are however required to conclude on the best treatment strategy for knee soft tissue injuries.

Plantar pressure measurements and running-related injury: A systematic review of methods and possible associations

Pressure-sensitive measuring devices have been identified as appropriate tools for measuring an array of parameters during running. It is unclear which biomechanical characteristics relate to running-related injury (RRI) and which data-processing techniques are most promising to detect this relationship. This systematic review aims to identify pertinent methodologies and characteristics measured using plantar pressure devices, and to summarise their associations with RRI. PubMed, Embase, CINAHL, ScienceDirect and Scopus were searched up until March 2015. Retrospective and prospective, biomechanical studies on running using any kind of pressure-sensitive device with RRI as an outcome were included. All studies involving regular or recreational runners were considered. The study quality was assessed and the measured parameters were summarised. One low quality, two moderate quality and five high quality studies were included. Five different subdivisions of plantar area were identified, as well as five instants and four phases of measurement during foot-ground contact. Overall many parameters were collated and subdivided as plantar pressure and force, plantar pressure and force location, contact area, timing and stride parameters. Differences between the injured and control group were found for mediolateral and anteroposterior displacement of force, contact area, velocity of force displacement, relative force-time integral, mediolateral force ratio, time to peak force and inter-stride correlative patterns. However, no consistent results were found between studies and no biomechanical risk patterns were apparent. Additionally, conflicting findings were reported for peak force in three studies. Based on these observations, we provide suggestions for improved methodology measurement of pertinent parameters for future studies.

Motor control of landing from a countermovement jump in simulated microgravity

Landing from a jump implies proper positioning of the lower limb segments and the generation of an adequate muscular force to cope with the imminent collision with the ground. This study assesses how a hypogravitational environment affects the control of landing after a countermovement jump (CMJ). Eight participants performed submaximal CMJs on Earth (1- g condition) and in a weightlessness environment with simulated gravity conditions generated by a pull-down force (1-, 0.6-, 0.4-, and 0.2- g0 conditions). External forces applied to the body, movements of the lower limb segments, and muscular activity of six lower limb muscles were recorded. 1) All subjects were able to jump and stabilize their landing in all experimental conditions, except one subject in 0.2- g0 condition. 2) The mechanical behavior of lower limb muscles switches during landing from a stiff spring to a compliant spring associated with a damper. This is true whatever the environment, on Earth as well as in environments where sensory inputs are altered. 3) The motor control of landing in simulated 1 g0 reveals an increased “safety margin” strategy, illustrated by increased stiffness and damping coefficient compared with landing on Earth. 4) The motor command is adjusted to the task constraints: muscular activity of lower limb extensors and flexors, stiffness and damping coefficient decrease according to the decreased gravity level. Our results show that even if in daily living gravity can be perceived as a constant factor, subjects can cope with altered sensory signals, taking advantage of the remaining information (visual and/or decreased proprioceptive inputs).

Muscle Activity Onset Prior to Landing in Patients after Anterior Cruciate Ligament Injury: A Systematic Review and Meta-Analysis

Muscle activation during landing is paramount to stabilise lower limb joints and avoid abnormal movement patterns. Delayed muscle activity onset measured by electromyography (EMG) has been suggested to be associated with anterior cruciate ligament (ACL) injury. Therefore, the aim of this systematic review and meta-analysis was to test the hypothesis if ACL-injured patients display different results for muscle onset timing during standard deceleration tasks compared to healthy control participants. PubMed, Embase, Scopus and ScienceDirect databases were systematically searched over the period from January 1980 to February 2015, yielding a total of 1461 citations. Six studies meeting inclusion criteria underwent quality assessment, data extraction and re-computing procedures for the meta-analysis. The quality was rated “moderate” for 2 studies and “poor” for 4. Patients included and procedures used were highly heterogeneous. The tasks investigated were single leg hopping, decelerating from running or walking, tested on a total of 102 ACL-injured participants and 86 controls. EMG analyses of the muscles vastus lateralis, vastus medialis, lateral and medial hamstrings revealed trivial and non-significant standardised mean differences (SMD<0.20; p>0.05) between patients and control participants. Furthermore, no differences were found between the contralateral leg of patients and controls for muscle activity onset of the medial and lateral gastrocnemius (SMD<0.20; p>0.05). Based on 3 studies, the involved legs of ACL-injured patients showed overall earlier muscle activity onset compared to control participants for the medial gastrocnemius (SMD = 0.5; p = 0.05). Similar results were found for the lateral gastrocnemius (SMD = 2.1; p<0.001), with a greater effect size but based only on a single study. We conclude that there are no differences between leg muscles of ACL-injured patients and healthy controls regarding the muscle activity onset during landing. However, current evidence is scarce and weak, which highlights the need for further research in this area.

A new quantitative measure for radiologic osteoarthritis of the lateral knee compartment distinguishes patients with longstanding lateral meniscectomy from non-pathological knees

PURPOSE

Common radiologic scores to evaluate knee osteoarthritis (OA) have been widely used but are descriptive and may lack objectivity. The aim of this study was to develop a quantitative and objective radiologic measure for the evaluation of lateral knee compartment OA. Furthermore, we tested the reliability of this new measure and its correlation to well-accepted radiologic scores.

METHODS

This retrospective study was performed within the context of a multi-centre long-term follow-up (15-25 years) of a patient cohort after partial or total lateral meniscectomy (n = 36 knees). In addition, 99 radiographs of clinically and radiologically normal knees were obtained from a control group. Anteroposterior weight-bearing views (0°) and Schuss (45°) views were analysed. The joint height of the lateral knee compartment was measured on the lateral border (lateral joint space height) and in the centre (central joint space height, CJSH) and normalized with respect to the width of the lateral compartment (X). All measurements were taken independently by two observers, allowing for inter- and intra-observer reliability assessments. The results of the two groups were compared using an analysis of covariance. Finally, the correlations between the results and the Fairbank and Kellgren & Lawrence scores were determined using a Spearman ρ rank order correlation.

RESULTS

The normalized joint space height in the centre of the compartment on the Schuss view (CJSH/X) showed the highest intra- (ICC = 0.980) and inter-observer reliability (ICC = 0.982). There was a significant difference in CJSH/X between the control (0.19 ± 0.05) and the meniscectomized knees (0.08 ± 0.07) (p < 0.001). CJSH/X showed a significant decline of 11 % per 10 years in the meniscectomy group. A negative correlation could be found between CJSH/X and the Fairbank (ρ = -0.751; p < 0.001) and Kellgren & Lawrence scores (ρ = -0.712; p < 0.001). A cut-off value of 0.14 of CJSH/X was defined-representing one standard deviation below the mean of the control group-from which measurements were considered as pathologic.

CONCLUSION

The normalized joint space height measured in the centre of the lateral knee compartment from a Schuss view, CJSH/X, was highly reproducible and showed a significant correlation to established radiologic scores. This new measure has the advantage of being objective and dimensionless and thus independent of the size of the radiograph. The normative values provided by our healthy control knees are useful to help establish an early diagnosis of radiologic lateral knee compartment OA.

LEVEL OF EVIDENCE

Retrospective diagnostic study, Level III.

Exercise and sports science Australia (ESSA) position statement on exercise and spinal cord injury

Traumatic spinal cord injury (SCI) may result in tetraplegia (motor and/or sensory nervous system impairment of the arms, trunk and legs) or paraplegia (motor and/or sensory impairment of the trunk and/or legs only). The adverse effects of SCI on health, fitness and functioning are frequently compounded by profoundly sedentary behaviour. People with paraplegia (PP) and tetraplegia (TP) have reduced exercise capacity due to paralysis/paresis and reduced exercising stroke volume. TP often further reduces exercise capacity due to lower maximum heart-rate and respiratory function. There is strong, consistent evidence that exercise can improve cardiorespiratory fitness and muscular strength in people with SCI. There is emerging evidence for a range of other exercise benefits, including reduced risk of cardio-metabolic disease, depression and shoulder pain, as well as improved respiratory function, quality-of-life and functional independence. Exercise recommendations for people with SCI are: ≥30min of moderate aerobic exercise on ≥5d/week or ≥20min of vigorous aerobic ≥3d/week; strength training on ≥2d/week, including scapula stabilisers and posterior shoulder girdle; and ≥2d/week flexibility training, including shoulder internal and external rotators. These recommendations may be aspirational for profoundly inactive clients and stratification into "beginning", "intermediate" and "advanced" will assist application of the recommendations in clinical practice. Flexibility exercise is recommended to preserve upper limb function but may not prevent contracture. For people with TP, Rating of Perceived Exertion may provide a more valid indication of exercise intensity than heart rate. The safety and effectiveness of exercise interventions can be enhanced by initial screening for autonomic dysreflexia, orthostatic hypotension, exercise-induced hypotension, thermoregulatory dysfunction, pressure sores, spasticity and pain.

There is no such thing like a single ACL injury: Profiles of ACL-injured patients

BACKGROUND

Current ACL registries rarely include non-operatively treated patients thus delivering an incomplete picture of the ACL-injured population. The aim of this study was to get an image of the population and treatment decision of an intrahospital registry. Our hypotheses were that patient-specific subtypes can be identified and that the percentage of operated patients differs between them.

MATERIAL AND METHODS

Three hundred and forty-six operated and non-operated patients were included from March 2011 to December 2013. Standardized questionnaires allowed for data collection on gender, age, sports practice and previous ACL injuries. Chi-square tests allowed to compare these parameters between genders and age groups. A cluster analysis was computed to determine profiles of patients with similar characteristics.

RESULTS

Three age groups were considered (I: ≤20; II: 21-35; III: ≥36 years). For males, the highest frequency of injuries was noted in group II with a greater proportion of injuries compared to females. In group III, more females were injured than males. Before injury, 54% patients were involved in competitive sports. Males were more likely to be injured in pivoting/contact sports before 35 and females during recreational skiing after 35. Twenty-one percent of the patients had had a previous ACL injury. The percentage of surgical treatment was superior to 80% in patients under 35 years involved in competitive sports, of 60-80% for those not involved in competitive sports and inferior to 60% for patients above 35 years.

DISCUSSION

Systematic data collection allowed to identify specific subtypes of ACL-injured patient according to gender, age, previous ACL injury and preinjury level of practice. The decision-making process for or against ACL reconstructions at time of presentation depended on these characteristics. Consideration of these parameters will serve as a basis for an individualized treatment approach and a better understanding of patients at risk for ACL injuries.

LEVEL OF EVIDENCE

III.

Injury risk in runners using standard or motion control shoes: a randomised controlled trial with participant and assessor blinding

Background/aim

This randomised controlled trial investigated if the usage of running shoes with a motion control system modifies injury risk in regular leisure-time runners compared to standard shoes, and if this influence depends on foot morphology.

Methods

Recreational runners (n=372) were given either the motion control or the standard version of a regular running shoe model and were followed up for 6 months regarding running activity and injury. Foot morphology was analysed using the Foot Posture Index method. Cox regression analyses were used to compare injury risk between the two groups, based on HRs and their 95% CIs, controlling for potential confounders. Stratified analyses were conducted to evaluate the effect of motion control system in runners with supinated, neutral and pronated feet.

Results

The overall injury risk was lower among the participants who had received motion control shoes (HR=0.55; 95% CI 0.36 to 0.85) compared to those receiving standard shoes. This positive effect was only observed in the stratum of runners with pronated feet (n=94; HR=0.34; 95% CI 0.13 to 0.84); there was no difference in runners with neutral (n=218; HR=0.78; 95% CI 0.44 to 1.37) or supinated feet (n=60; HR=0.59; 95% CI 0.20 to 1.73). Runners with pronated feet using standard shoes had a higher injury risk compared to those with neutral feet (HR=1.80; 95% CI 1.01 to 3.22).

Conclusions

The overall injury risk was lower in participants who had received motion control shoes. Based on secondary analysis, those with pronated feet may benefit most from this shoe type.

Promotion of physical activity in patients with non-communicable diseases in Luxembourg: a follow-up of the Sport-Sante inventory from 2014

Regular practice of physical activity (PA) has many health benefits in both healthy individuals and in people with non-communicable diseases (NCDs). In order to disseminate this evidence and to strengthen the promotion of PA in people with NCDs, the Sport-Santé project was created in Luxembourg and officially launched in April 2015. In 2014, a stocktaking of the different organizations offering PA for people with NCDs was realized in order to develop the Sport-Santé project. Different communication tools were used to promote Sport-Santé as well as the aforementioned organizations. The present study aimed to re-evaluate the offers of PA for people with NCDs in Luxembourg one year after the launch of the project. The organizations offering PA for people with NCDs (orthopaedics, obesity and overweight, neurology and rare diseases, oncology and cardiology) were screened in 2014 and in 2016. The number of weekly offered hours of PA for people with NCDs were collected and the participation rate was observed. Participants (192 in 2014 and 196 in 2016) volunteered to answer a survey, which contained questions regarding their age, sex, time since enrolment, travel distance, former and current PA participation, and type of recruitment. Additional items regarding prescription and refund were explored only in 2016. In 2016, more than 55 hours per week of PA were offered for people with NCDs in Luxembourg (≈44 hours per week were identified in 2014). However, this increase was not statistically significant. No difference was observed between 2014 and 2016 regarding the participation rate (2014: 8.9 ± 5.1 participants per hour; 2016: 8.4 ± 5.7 participants per hour). Participants were younger in 2016 than in 2014. The time since enrolment was shorter in 2016 than in 2014. No difference between 2014 and 2016 was observed for travel distance, sex distribution, former and current PA participation, and type of recruitment. Participants were mainly recruited by the healthcare professionals. More than 69 % of the participants would like to receive a medical prescription for the PA. Fifty-two percent of the participants would appreciate a refund of the participation fees by their health insurance. The increasing efforts of Sport-Santé and the organizations offering PA for people with NCDs lead to increase the offer. However, the participation rate remains unchanged. The decrease in age and in time since enrolment observed in 2016 could be explained by the creation of new activities, a larger participant's turnover or high number of withdrawals among long-term participants. Even if participants are mainly recruited by healthcare professionals, this type of recruitment can be attributed to very few idealists. All healthcare professionals should be aware of the offers of Sport-Santé and advise their patients to participate in a PA program. It is now time to advance the idea of prescription of PA as a privileged treatment option and to convince the policymakers to take action against sedentary behaviours in Luxembourg. Nevertheless, this type of promotion is not enough to increase the number of participants and additional strategies must be explored and developed. The best sustainable strategies are always those that approach the problem from different viewpoints.

Sitagliptin plus granulocyte colony-stimulating factor in patients suffering from acute myocardial infarction: A double-blind, randomized placebo-controlled trial of efficacy and safety (SITAGRAMI trial)

OBJECTIVE

In animal models, G-CSF based progenitor cell mobilization combined with a DPP4 inhibitor leads to increased homing of bone marrow derived progenitor cells to the injured myocardium via the SDF1/CXCR4 axis resulting in improved ejection fraction and survival after acute myocardial infarction (AMI).

RESEARCH DESIGN AND METHODS

After successful revascularization in AMI, 174 patients were randomized 1:1 in a multi-centre, prospective, placebo-controlled, parallel group, double blind, phase III efficacy and safety trial to treatment with G-CSF and Sitagliptin (GS) or placebo. Diabetic and non-diabetic patients were included in our trial. The primary efficacy endpoint hierarchically combined global left and right ventricular ejection fraction changes from baseline to 6 months of follow-up (ΔLVEF, ΔRVEF), as determined by cardiac MRI.

RESULTS

At follow-up ΔLVEF as well as ΔRVEF did not differ between the GS and placebo group. Patients in the placebo group had a similar risk for a major adverse cardiac event within 12 months of follow-up as compared to patients under GS.

CONCLUSION

Progenitor cell therapy comprising the use of G-CSF and Sitagliptin after successfully revascularized acute myocardial infarction fails to show a beneficial effect on cardiac function and clinical events after 12 months. (EudraCT: 2007-003,941-34; ClinicalTrials.gov: NCT00650143, funding: Heinz-Nixdorf foundation).

Motor Control of Landing from a Jump in Simulated Hypergravity

On Earth, when landing from a counter-movement jump, muscles contract before touchdown to anticipate imminent collision with the ground and place the limbs in a proper position. This study assesses how the control of landing is modified when gravity is increased above 1 g. Hypergravity was simulated in two different ways: (1) by generating centrifugal forces during turns of an aircraft (A300) and (2) by pulling the subject downwards in the laboratory with a Subject Loading System (SLS). Eight subjects were asked to perform counter-movement jumps at 1 g on Earth and at 3 hypergravity levels (1.2, 1.4 and 1.6 g) both in A300 and with SLS. External forces applied to the body, movements of the lower limb segments and muscular activity of 6 lower limb muscles were recorded. Our results show that both in A300 and with SLS, as in 1 g: (1) the anticipation phase is present; (2) during the loading phase (from touchdown until the peak of vertical ground reaction force), lower limb muscles act like a stiff spring, whereas during the second part (from the peak of vertical ground reaction force until the return to the standing position), they act like a compliant spring associated with a damper. (3) With increasing gravity, the preparatory adjustments and the loading phase are modified whereas the second part does not change drastically. (4) The modifications are similar in A300 and with SLS, however the effect of hypergravity is accentuated in A300, probably due to altered sensory inputs. This observation suggests that otolithic information plays an important role in the control of the landing from a jump.

Combined anterior and rotational knee laxity measurements improve the diagnosis of anterior cruciate ligament injuries

PURPOSE

This study analysed whether associating the side-to-side difference in displacement and the slope of the load-displacement curve of anterior and rotational knee laxity measurements would improve the instrumental diagnosis of anterior cruciate ligament (ACL) ruptures and help to detect different types of ACL tears.

METHODS

Anterior and rotational knee laxity was measured in 128 patients with an arthroscopically confirmed ACL injury and 104 healthy controls. Side-to-side differences were determined for three variables in anterior laxity: anterior displacement at 200 N (ATD200), primary compliance from 30 to 50 N (PCA) and secondary compliance from 100 to 200 N (SCA). Furthermore, four variables in rotational laxity were considered: internal and external rotation at 5 N m (IR5/ER5) and compliance from 2 to 5 N m (C IR/C ER). Receiver operating characteristic curves allowed to determine thresholds, specificities and sensitivities to detect ACL lesions, based on single variables considered and combinations thereof.

RESULTS

Sensitivity and specificity reached, respectively, 75 and 95 % for ATD200 (threshold: 1.2 mm) and 38 and 95 % for IR5 (threshold: 3.2°). If either two out of the three variables were positive for anterior laxity or both IR5 and C IR were positive, 81 % of patients were identified without a false positive. All patients for whom ATD200 was >3.7 mm, PCA > 48 μm/N or SCA > 17.5 µm/N had ACL remnants that were either totally resorbed or healed on the posterior cruciate ligament.

CONCLUSION

Combined instrumented anterior and rotational knee laxity measurements have excellent diagnostic value for ACL injury, provided that several measurements be considered concomitantly.

LEVEL OF EVIDENCE

Diagnostic study, Level III.

Noninjured Knees of Patients With Noncontact ACL Injuries Display Higher Average Anterior and Internal Rotational Knee Laxity Compared With Healthy Knees of a Noninjured Population

BACKGROUND

Excessive physiological anterior and rotational knee laxity is thought to be a risk factor for noncontact anterior cruciate ligament (ACL) injuries and inferior reconstruction outcomes, but no thresholds have been established to identify patients with increased laxity.

PURPOSE

(1) To determine if the healthy contralateral knees of ACL-injured patients have greater anterior and rotational knee laxity, leading to different laxity profiles (combination of laxities), compared with healthy control knees and (2) to set a threshold to help discriminate anterior and rotational knee laxity between these groups.

STUDY DESIGN

Case-sectional study; Level of evidence, 3.

METHODS

A total of 171 healthy contralateral knees of noncontact ACL-injured patients (ACL-H group) and 104 healthy knees of control participants (CTL group) were tested for anterior and rotational laxity. Laxity scores (measurements corrected for sex and body mass) were used to classify knees as hypolax (score <-1), normolax (between -1 and 1), or hyperlax (>1). Proportions of patients in each group were compared using χ(2) tests. Receiver operating characteristic curves were computed to discriminate laxity between the groups. Odds ratios were calculated to determine the probability of being in the ACL-H group.

RESULTS

The ACL-H group displayed greater laxity scores for anterior displacement and internal rotation in their uninjured knee compared with the CTL group (P < .05). Laxity profiles were different between the groups for the following associations: normolax in anterior displacement/hypolax in internal rotation (6% [ACL-H] vs 15% [CTL]; P = .02) and hyperlax in anterior displacement/normolax in internal rotation (27% [ACL-H] vs 10% [CTL]; P < .01). The laxity score thresholds were 0.75 for anterior laxity and -0.55 for internal rotation. With both scores above these thresholds, a patient was 3.18-fold more likely to be in the ACL-H group (95% CI, 1.74-5.83).

CONCLUSION

The healthy contralateral knees of patients with noncontact ACL injuries display different laxity values both for internal rotation and anterior displacement compared with healthy control knees. The identification of knee laxity profiles may be of relevance for primary and secondary prevention programs of noncontact ACL injuries.